Pulmonary embolism is the sudden blockage of a major artery in the lung. This is usually due to a blood clot that developed in another part of the body, broke off and travelled with the blood stream into the lung circulation, blocking the pumping of the heart and oxygen uptake. The most frequent source of these blood clots (thrombi) is the deep vein circulation of the legs, a condition known as deep vein thrombosis.

What is PE?

Depending on the size of the blood clot, pulmonary embolism can cause heart or lung damage and can be a life threatening condition. Prompt treatment could save your life or reduce the risk of future problems.

There are a variety of risk factors that contribute to the development of pulmonary embolism. Practically, anything that makes you more likely to form blood clots increases your risk of pulmonary embolism:

  • Surgery, particularly orthopedic surgery (e.g. hip or knee), or abdominal surgery
  • Trauma or bone fracture
  • A long period of bed rest or sitting for a long time (e.g. on an airplane or in a car)
  • Cancer and some of its treatments (e.g. chemotherapy)
  • Cardiovascular diseases such as atrial fibrillation, heart failure, heart attack or stroke
  • Pregnancy and the first 6 weeks after giving birth
  • Birth control pills or hormones taken for symptoms of menopause
  • Family history of blood clots
  • Inherited blood disorders that make the blood thick (e.g. thrombophilia)
  • Inflammatory bowel disease
  • Autoimmune diseases (e.g. lupus, antiphospholipid syndrome)
  • Smoking
  • Obesity
  • Placement of vein catheters, pacemakers or implantable defibrillators  

Although these risk factors increase a person's risk, they do not necessarily cause the disease. Some people with one or more risk factors never develop the disease, while others develop disease and have no known risk factors, indicating the effect of the genes (family history).